drm/nouveau: rip out nvkm_client.super

No longer required now that userspace can't touch anything that might
need it, and should fix DRM MM operations racing with each other, and
the random hangs/crashes that come with that.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>

drm/nouveau/dma: lookup objects with nvkm_object_search()

Custom code is no longer needed here.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drm/nouveau/nvif: modify nvif_unvers/nvif_unpack macros to be more obvious

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drm/nouveau/nvif: split out ctxdma interface definitions

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drm/nouveau/dma: convert user classes to new-style nvkm_object

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drm/nouveau/dma: split user classes out from engine implementations

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>